David Nistér Frederik Schaffalitzky What Do Four Points in Two Calibrated Images Tell Us about the Epipoles? 41-57 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3022&spage=41 2004 conf/eccv/2004-2 ECCV (2) db/conf/eccv/eccv2004-2.html#NisterS04